Software appliances can consist of a software package in which services and user interfaces (UIs) run on top of an operating system such as Linux™, to provide support for a top-level application. Software appliances can be provided for download over the Internet by independent software vendors (ISVs) or other sources. Users of a given software appliance may eventually decide to upgrade or update the appliance to a newer version.
Performing an appliance update to install the new version can pose difficulties to the user. A user can for instance download an executable file to perform an in-place installation of the new version of an appliance. The new version is extracted and installed over the old version. In the process of installation, the configuration state of the old version is lost. That is, the user's chosen preferences and configuration data is wiped out, leaving the new version in a default configuration that does not incorporate all the user settings from the old version of the software appliance. The new version instead reverts to a default configuration state. The user must then go back to manually reconfigure the new version of the appliance to duplicate the settings the user had developed on the old version. This may also be attempted by running a restore operation from a streaming backup tape, which in some facilities can take days of time. In addition, the accumulated user data produced by the user operating the old version can be lost upon installation of the new appliance. Alternatively, the new version of the software appliance can attempt to import the previously existing user data files, but in the event that the data schema of the new version has changed compared to the old version, there may be incompatibilities when attempting to recover or operate on that data. It may be desirable to provide methods and systems for updating software appliances that overcome these and other problems in the art.